Ring circle

I am having an issue with this ring circle

This is what I have now:
exten => 8888888888,n,Dial(SIP/412&SIP/413&SIP/422&SIP/423&SIP/424&SIP/425,20,t)
exten => 8888888888,n,Dial(SIP/1452@ast-wex01)
exten => 8888888888,n,Dial(SIP/2

I have a persistent problem and I want to break the ring circle it into (2) smaller ring groups where 3 extensions ring first and then the other 3 extensions ring.

First rings go to extensions 422, 423 and 413

If no one answers, second rings go to extensions 412, 424 & 425

Can anyone help with add this new ring circle?